This VI was originally designed for testing and controlling various types of thermoelectric coolers (TEC / Peltier) by using a programmable power supply, CompactDAQ + C modules as well as a PID Control algorithm. While this application was specifically developed for TEC, it may also be used for other slow speed applications requiring a PID controller. Additional features include Auto/Manual mode, delta temperature set/monitor warning, real-time process variable versus target temperature strip chart, parameter monitoring and data logging.
The PID section uses three analog input channels for temperature sensor inputs (hot/cold and ambient), a digital line to generate a low frequency (few hertz) pulse width modulated (PWM) output to power the TEC under test. When the advanced PID algorithm is in manual mode, you can set the output power level (pulse width) anywhere from 0 to 100% by adjusting the “%Manual Power Control” knob. When in auto mode, the pulse width is adjusted according to the PID gain setting.
The power supply section consist of programmable voltage ranging from 0 to 50 volts at 7Amps (model dependent), up to 21Amps with multiple power supplies connected in parallel, power output polarity control, fan control in continuous or PWM mode, emergency shutdown as well as waveform strip chart in addition to the parameter monitoring displays.
How It Works:
The ambient temperature is used for reference, temperatures above ambient are considered “Hot” and temperatures below ambient are “Cold”. For hot temperature controlling, TC0 is used as a feedback to the PID controller, and for the cold temperature TC1 is used for feedback. Figure 1 is simplified block diagram of the multi-function TEC controller.
Figure 1. Multi-Function TEC Controller Block Diagram
Power Supply Main Features:
PID Controller Main Features:
Instructions: Power supply setting:
Instructions: PID Controller:
Hardware:
Thermocouple inputs:
Three thermocouple input lines are used for monitoring temperatures as follows:
Analog inputs lines:
Two analog input lines are used for monitoring power supply voltage and current as follows:
Analog output:
One Analog output line is used for adjusting power supply output voltage (0 to 5V corresponds to 0 to 50V)
Digital I/O Lines:
Four digital lines are used for controlling power supply, relays and fan as follows:
The following 3 figures are sample snapshots of TEC at various operating condition.
Figure 2, TEC default setting
Figure 3, TEC with DC voltage supply
Figure 4, TEC with PWM output control
Ready to Run TEC Controller
This is a ready-to-run TEC control application using NI-DAQmx driver software and CompactDAQ hardware. The application is in executable format and was developed on Windows XP professional and only requires LabVIEW 9.0 Run-Time Engine (included) to execute. You can download the zipped file from the following link that includes both application and installer. If you have LabVIEW professional development system 2009 (Ver 9.0f3 or later) and PID toolset, and would like to have a copy of this VI, send us an email (info@ScientificRFA.com) to request for a copy.
Installation: Extract to C:\ drive and double click the setup
The following videos demonstrate different scenarios using the Multi-Function TEC controller system.
PID temperature controller from sub-zero to near boiling water demo
CPU Cooler Performance Test
Extreme Sub-zero Temperature Regulator